This invention relates to impact-absorbing transverse support arrangements, for example, of the type used to absorb collision-generated impact forces in motor vehicles.
Transverse support arrangements for absorbing impact forces are generally designed to absorb forces applied in a direction transverse to the longitudinal extent of the member. Accordingly, in the preferred application of the invention, i.e., the absorption of collision-generated impact forces in motor vehicles, this transverse support arrangement may constitute a component of a shock absorber, a knee bar, a sill, a door column, a ramming buffer or any other transverse support arrangement which, in the event of a collision, is subject to impact forces produced by an external object or by the inertia of passengers in the vehicle.
Particularly in the preferred application of the invention, it is important that the transverse support arrangement is not simply preserved upon the occurrence of impact forces, but that it is capable of converting the kinetic energy of the impact forces into deformation work. In other words, the transverse support arrangement should be designed so that its cross-section can be deformed upon application of impact forces. In addition, in the preferred application of the invention, namely, in motor vehicles, it is necessary to convert the impact energy into deformation work to the greatest possible extent in a short deformation path. This is especially true when the transverse support arrangement is arranged along the side of a vehicle or is positioned as a knee bar in the knee room of the vehicle, since the space required for long deformation elements is not available in those cases.
A transverse support arrangement of this type is disclosed in U.S. Pat. No. 4,893,834 in the form of a knee bar having two adjacent transverse support sections, the first of which has a closed rectangular cross-section and the second having an essentially open semicircular cross-section which is attached to the body of the automobile by flanges at the open side of its cross-section. Because of the continuous curvature of the cross-section of the second section, the latter forms a linear support, extending parallel to the longitudinal direction of the first support section, and providing a support surface for the closed rectangular first support section. The first support section has a very rigid design in comparison to the second support section since it is intended to distribute the locally concentrated compressive forces produced by impact of the knee of a passenger in the vehicle as a result of a collision over as large a longitudinal portion of the second support section as possible. Because the width of the first support section is less than that of the second support section, deformation of the second support section takes place essentially by reverse deformation of the side walls of that section in such a way that the first section is pressed into the body of the second section.
This conventional transverse support arrangement has several disadvantages. For one thing, the use of a second support section having an open cross-section with flanges requires the presence of parts on the automobile body to which the flanges of the second support section are attached and, accordingly, necessitates appropriate design of these body parts. Secondly, the manufacture of this conventional transverse support arrangement is exceptionally cumbersome and costly since the two support sections are made in separate operations and are then joined together by screws. These screw connections require the second support section to have an open cross-section since otherwise it would hardly be possible to provide the screw connections.